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Development and implementation of a limit equilibrium procedure for the three-dimensional analysis of asymmetric landslides Burden, Justin Matthewson
Abstract
Two-dimensional limit equilibrium types of analysis have been used in engineering practice for decades and are the most commonly adopted analysis technique for assessing the stability of slopes. These methods compute a factor of safety based on a comparison of available to required shear strength along a prescribed failure surface. Forces and static equilibrium conditions are only considered in the plane of movement. However, in reality, all slope failures occur in three-dimensions. Every sliding mass has a finite length and shear forces acting at the lateral extents of the mass contribute to the resistance to movement. Errors introduced by neglecting the three-dimensional character of a slide cannot be overlooked in all cases. Examples include deep narrow excavations, convex/concave slope geometries, slopes that fail by narrow localized failure and structurally controlled failures in rock. Consideration of threedimensional effects may be of particular importance where computed two-dimensional factors of safety are marginal or when back-analyzing slope failures where derived shear strengths should reflect the influence of end effects. This thesis details the development, implementation and evaluation of a general limit equilibrium method of columns procedure suitable for analyzing the three-dimensional stability of asymmetric landslides. The proposed method, termed the three-dimensional asymmetric Spencer method, uses internal force functions to satisfy the equilibrium conditions. Unlike many of its predecessors, the algorithm satisfies force and moment equilibrium in both horizontal directions. The direction of sliding is not assumed, but rather determined explicitly in the analysis. The solution scheme is implemented in the computer program J3D. A moment balancing procedure is developed and used to investigate the effect of enforcing moment equilibrium about a vertical axis of rotation on the analysis results. Analyses completed using J3D are compared with solutions derived using existing limit equilibrium methods and three-dimensional distinct element models for several asymmetric slide examples, including the Kettleman Hills Landfill case history. Preliminary results indicate that the three-dimensional asymmetric Spencer method is well suited for the analysis of general slope stability cases, including asymmetric problems. Application of the proposed moment balancing algorithm may only be suitable for problems involving specialized slope and slip surface geometries.
Item Metadata
Title |
Development and implementation of a limit equilibrium procedure for the three-dimensional analysis of asymmetric landslides
|
Creator | |
Publisher |
University of British Columbia
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Date Issued |
2013
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Description |
Two-dimensional limit equilibrium types of analysis have been used in engineering practice for
decades and are the most commonly adopted analysis technique for assessing the stability of
slopes. These methods compute a factor of safety based on a comparison of available to
required shear strength along a prescribed failure surface. Forces and static equilibrium
conditions are only considered in the plane of movement. However, in reality, all slope failures
occur in three-dimensions. Every sliding mass has a finite length and shear forces acting at the
lateral extents of the mass contribute to the resistance to movement. Errors introduced by
neglecting the three-dimensional character of a slide cannot be overlooked in all cases.
Examples include deep narrow excavations, convex/concave slope geometries, slopes that fail
by narrow localized failure and structurally controlled failures in rock. Consideration of threedimensional
effects may be of particular importance where computed two-dimensional factors of
safety are marginal or when back-analyzing slope failures where derived shear strengths should
reflect the influence of end effects.
This thesis details the development, implementation and evaluation of a general limit equilibrium
method of columns procedure suitable for analyzing the three-dimensional stability of
asymmetric landslides. The proposed method, termed the three-dimensional asymmetric
Spencer method, uses internal force functions to satisfy the equilibrium conditions. Unlike many
of its predecessors, the algorithm satisfies force and moment equilibrium in both horizontal
directions. The direction of sliding is not assumed, but rather determined explicitly in the
analysis. The solution scheme is implemented in the computer program J3D. A moment
balancing procedure is developed and used to investigate the effect of enforcing moment
equilibrium about a vertical axis of rotation on the analysis results.
Analyses completed using J3D are compared with solutions derived using existing limit
equilibrium methods and three-dimensional distinct element models for several asymmetric slide
examples, including the Kettleman Hills Landfill case history. Preliminary results indicate that
the three-dimensional asymmetric Spencer method is well suited for the analysis of general
slope stability cases, including asymmetric problems. Application of the proposed moment
balancing algorithm may only be suitable for problems involving specialized slope and slip
surface geometries.
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Genre | |
Type | |
Language |
eng
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Date Available |
2013-01-29
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0073558
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2013-05
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International